In conjunction with the design and testing of various products, e.g. consumer electronic goods and military products, vibration forces are applied to the product along selected axes thereof to determine if the product can tolerate such forces and continue to function properly. Because it is typically time consuming and somewhat difficult to attach and detach an object to be vibration tested from a vibration source, e.g. a shaker table, fixtures have been developed for facilitating mechanically coupling the object with the vibration source. These fixtures generally comprise a base which is securely attached to the vibration source and at least one mounting surface to which the object to be vibration tested can be quickly and easily attached.
One such fixture is disclosed in British patent application Ser. No. 8,522,501, filed Sep. 11, 1985. This fixture has a cubic shape. The object to be vibration tested is attached to one face of the cube and another face of the cube is secured to a vibration source. By releasing the cube from the vibration source after a vibration test is completed and rotating the former about its diagonal axis 120 degrees, a new face of the cube is positioned for attachment to the vibration source. By this selective rotation of the cubic fixture, vibration forces can be applied along three mutually-orthogonal axes of the object without the need for removing the object from the test fixture after each test. Rotation of the cubic fixture is effected either manually or by means of an electric motor.
Another vibration test apparatus is disclosed in U.S. patent application Ser. No. 265,310, filed Oct. 25, 1988, now U.S. Pat. No. 4,848,160 . The latter apparatus comprises a cubic fixture for supporting an object to be vibration tested, a head expander positioned between the cubic fixture and a vibration source, an index assembly for raising the cubic fixture away from and lowering the cubic fixture onto the head expander, and a rotation assembly for rotating the cubic fixture about its diagonal axis when the fixture is raised above the head expander. The apparatus also includes a controller for automatically raising, rotating and lowering the cubic fixture so that vibration testing can be performed along three mutually-orthogonal axes of the test object without detaching the object or the cubic fixture on which it is supported from the vibration source during the three-test sequence.
Although the vibration test apparatus of application Ser. No. 265,310 functions satisfactorily in most circumstances, where, for instance, objects are vibration tested in assembly-line fashion using unskilled or low-skilled personnel, it has been determined that the '310 apparatus can be too complicated for the average employee to operate. As such, vibration testing must be performed using fixtures which require detachment of the test object and/or fixture after a vibration test is performed along each of the axes of the object of interest. Clearly, it is undesirable from a work efficiency perspective, where a multiple axis vibration test is to be performed, to attach and detach an object after each of the vibration tests.